I spoke with an engineer from stop tech (centric parts) and tried to find a rear rotor that would work with the rear Brembos calipers, and was unsuccessful...however the call was not a total loss because he looked at some data and after telling him the known rear caliper options for the car, he recommended the C5 or V8 F-Body (identical) rear brakes to best match the Brembos up front. He added that the difference would be minimal, but noticable especially with big wheels, on a FWD car but that the extra stopping power in back would be safe (as in not cause oversteer) because of how much stopping power the Brembos provide up front.
I looked into it and for both rear calipers and the GXP caliper brackets is under $100
